it is better to avoid heavy weights and concentrate on proper technique and form at 14. Some champions start early and are not affected and some are affected...some have professional bone deformation and some don't ....it is hard to tell
medically speaking it won't stunt growth if done properly, however heavy weights can lead to poor form and can hurt growth plates of the bones which will affect growth...
make child lift at 12, start the gears at 12 1/2. Proceed with heavy gear cycle at 13, continue administering vigerous workout regime with extreme anabolic use - Found this in the 1965 Russian Olympic powerlifting manual (say with russian accent, sounds better)
I have three boys 16,14,11. All of them are diffent 16yo is 6' 200lbs benches 315, 14 yo is 5"5 146 , 11yo 4'10 110. They all develope diffently. My oldest son likes drop sets and compound movements, middle like isolated movements, m youngest high reps perfect form. They feeed off each other. Just being in the gym keeps them away from all the others traps in life